Geotechnical Aspects on Seismic Risk Assessment in Cusco, Peru

Results from many efforts to better understand the nature of ground motions and the seismic behavior or structures in Cusco, Peru, give now the possibility to combine several sources of information to produce estimates of seismic hazard and risk. A model is presented which estimates expected damage, based on geotechnical characteristics and intensity-damage relations derived for several types of buildings representative of Cusco’s constructions. The study area was divided into smaller sections covering the whole city. This information, along with the geographic distribution of soil types and construction density, allows computation of expected losses during a given event for sites distributed throughout the city

The equilibrium flow and mass balance of the Taku Glacier, Alaska 1950?2006

International audienceThe Taku Glacier, Alaska has advanced 7.5 km since the late nineteenth century, while all other primary outlet glaciers of the Juneau Icefield are in retreat. The Juneau Icefield Research Program has completed field work on the Taku Glacier annually since 1946. The collected observations of surface mass balance, glacier velocity and glacier thickness at Profile IV 29 km above the terminus and 4 km above the equilibrium line provide a means to assess the equilibrium nature of the Taku Glacier. Velocity measured over a twelve month span and annual summer velocity measurements completed at a Profile IV from 1950?2006 indicate insignificant variations in velocity seasonally or from year to year. The consistency of velocity over the 56-year period indicates that in the vicinity of the equilibrium line, the flow of the Taku Glacier has been in an equilibrium state. Surface mass balance was positive from 1946?1988 averaging +0.42 m a?1. This led to glacier thickening. From 1988?2006 an important change has occurred and annual balance has been ?0.14 m a?1, and the glacier thickness has ceased increasing along Profile IV. Field measurements of ice depth and surface velocity allow calculation of the volume flux at Profile IV. Volume flux is then compared with the surface balance flux from the region of the glacier above Profile IV, determined annually in the field. Above Profile IV the observed mean surface flux is 5.50×108 m3/a (±5%), while the calculated volume flux range flowing through profile IV is 5.00?5.47×108 m3/a. The mean surface flux has been greater than the volume flux, which has led to slow thickening of the Taku Glacier up to 1988. The thickening has not led to a change in the flow of Taku Glacier at Profile IV